Roller journal for hot-gas swept bowl mills



Nov. 28, 1950 G. H. FRANGQUIST ROLLER JOURNAL FOR HOT-GAS SWEPT BOWLMILLS Filed Oct. 4, 1946 INVENTOR. Gustav H. Frongqui st (Ma 3&5

Patented Nov. 28, 1950 ROLLER JOURNAL FOR HOT-GAS SWEPT BOWL MILLSGustav H. Frangquist, Chicago, Ill., assignor to i CombustionEngineering-Superheater, Inc., a

corporation of Delaware Application October 4, 1946, Serial No. 701,096

This invention relates to mill journals and particularly to improvementin bushings forming the bearing surfaces between a mill roller and theshaft upon which it rotates.

In mills, such as the Raymond bowl mills, disclosed in the U. S. patentto Crites No. 2,079,155 (issued May 4, 1937, for Bowl Mill), amultiplicity of large grinding rollers generally rotate in spacedrelation with respect to and inside of a ring and the material to beground is fed between the rollers and the ring to be groundtherebetween. Because of the high temperatures that may prevail within amill when hot gases pass through the mill for the purpose of drying thematerial being ground, large clearances are provided between the rollerbushing and shaft to allow for expansion of the parts. Because of theheavy, unevenly distributed thrust against the rollers and the largeclearances in the journal bushings, it has been found that thesebushings deform and have actually seized the shaft. It is an object ofthis invention to provide an improved bearing which will overcome thisdifficulty.

In the accompanying drawings: Figure 1 is a cross section through aroller and its bearing, showing it mounted within a portion of the mill;and Figure 2' is a cross section of a portion of Figure 1 showing theimproved roller bearing of the invention. 7

In Figure 1 a circular bowl Ill having an upwardly projecting wall I Iis mounted for rotation around shaft I2. A circular grinding ring I3 isremovably mounted within wall H, the inner or grinding surface of thering being spaced from tangential contact with roller 44. As the bowland with it ring l3 rotates, the material to be ground, which iscontinuously fed into the bowl, will move by centrifugal force towardand onto the grinding surface of ring I 3 and thence between the rollerl4 and the ring I3 by rotation of the ring. In passing between theroller and ring, the material is ground, which exerts a force againstthe roller in a general direction radial to the roller, as approximatedby arrow I5.

The roller it comprises a wearing ring it. mounted on a lower journalhousing H, which is fastened to an upper journal housing I8 by bolts 19engaging the flanges 26 and 2! of the journal housings. Within lowerjournal housing I! is bushing 22 and within upper journal housing I8 isbushing 23. Bushings 22 and 23 have their upper edges provided withflanges 24 and 25 respectively, which are fastened to the journalhousings I1 and I8 by pins 26 and 21 so that the 4 Claims. (Cl. 241293)I bushing will rotate with the journal housings and rollers. Lowerjournal housing I! has a recess 28 at its upper end to accommodate anannularly arranged group of roller bearings 29.

The assembled roller, journal, housing and bushings rotate around shaft30. Shaft is provided with flange 3| which extends into recess 28 andserves as a bottom support for roller bearings 29 which, in turn,support the upper journal housing I 8 and thereby supports the lowerjournal housing I! and roller ring l6. Shaft 30 is fixedly supported injournal head 32 by means of a tapered shaft end and sleeve 33 heldtogether by a locknut 34 engaging threaded shaft end 35 and the top ofjournal head 32. The journal head is provided with an integral bearing31 for rotatably mounting it on a trunnion shaft 38.

Extending from bearing 31 is lever arm 39 whose end 40 bears upwardlyagainst stop bar 4| and downwardly against spring bearing cap 42. Spring43 bears upwardly against cap 42 and downwardly against spring seat 44.Both stop bar 4| and spring seat 44 are mounted by long threaded bolts45a in fixed relation to the mill housing 46a.and are verticallyadjustable with respect to the housing by means of said bolts. Byraising or lowering the stop bar 4|, lever 39 is raised or lowered androllers 14 are spaced nearer to or farther from grinding ring I3. Byraising or lowering spring seat 44 the upward force against lever end 40may be increased or decreased and thereby the resistance of the rollersE4 to being separated from the grinding surface of ring l3 by thematerial being ground.

This resisting force is of substantial magnitude and acts in a generaldirection radial to the roller, as approximately indicated by arrow Hi.The force 15 causes bushing 22 within the lower journal housing E1 tobear against shaft 30 at its lower end and the weight of the upperjournal housing I8 causes the bushing 23 to bear against the shaft 30 atits upper end in the opposite direction to force 15. Because of therelatively large clearances provided between the roller bushings 22 and23 and the shaft 30, the axis JJ of the assembled roller journalhousings and bushings will tend to tilt with respect to the axis SS ofthe shaft as shown in Figure 1. This tilting causes the upper portion ofbushing 22 to receive a relatively high bearing pressure where shown byarrow 45. Since this pressure is directly opposite flange 24 of bushing22 and since the flange is unsupported in the direction of pressure 45,this pressure 45 causes a turning moment around a support at the loweredge of the recess 28 of lower housing 22, the support beingapproximately shown by arrow 46. It has been found that this turningmoment has caused the upper portion of lower bushing 22 to be rolledinwardly toward the shaft as shown by dotted lines 41 and to causeseizure of the bearing where the inwardly extending portion bearsagainst the shaft.

According to the invention, a recess 48 (Figure 2) is provided at theupper edge of bushing 22 which extends downwardly at least to the top ofthe shoulder 49 of the lower journal housing I! at the bottom of theroller bearing recess 28. By so doing it has been found that all bearinseizures were eliminated, because the turning moment above mentioned nolonger exists since the pressure acting at 45 has been removed and theupper portion of the bushing 22 is under direct compression as shown bythe opposed arrows .50 in Figure 2. Preferably an additional recess 5|is provided on the top face of flange 24 of bushing :22 which has beenfound beneficial to the bushing.

While the preferred embodiment of the invention has been shown anddescribed, it will be understood that minor changes in construction andarrangements of parts and equivalent applications of the invention maybe made without departing from the spirit of the invention as claimed.

What I claim is:

1. In a bowl mill for grinding relatively cool material and for dryingsaid material by exposure to relatively hot gases, the combination of asubstantially vertical shaft exposed to an atmosphere of said hot gases;a roller surrounding the lower portion of said shaft for rotation withrespect thereto and being in close contact with and cooled by theaforesaid cool material; a journal housing within said roller serving asa mounting for the roller; a bushing positioned in said'journal housingintermediate it and said shaft to rotate within the housing on the shaftand protruding at the upper end beyond the surrounding housingscontacting wall, said bushing fitting loosely over said shaft to provideclearance between the bushing and shaft for thermal expansion of saidshaft; and a circumferential recess at the protruding end of saidbushing and on the interior side thereof, said recess extendingdownwardly adjacent said shaft for at least the axial length of thebushing protrusion, whereby side thrusts on said roller which are set upby grinding said cool material in the bowl mill and which imposeconcentrated forces on said bushings upper portion adjacent itsprotruding end are prevented from deforming the bushing wall in a Waythat otherwise might occur with resultant seizure of said shaft.

2. In a bowl mill for grinding relatively cool material and for dryingsaid material by exposure to relatively hot gases, the combination of anonrotating substantially vertical shaft exposed to an atmosphere ofsaid hot gases; a roller surrounding the lower portion of said shaft forrotation with respect thereto and being in close contact with and cooledby the aforesaid cool material; a journal housing within said rollerserving as a mounting for the roller and having means forming acircumferential recess in its upper portion; a bushing positioned insaid journal housing intermediate it and said shaft to rotate with thehousing on the shaft, said bushing fitting loosely over said shaft toprovide clearance between the bushing and shaft for thermal expansion ofsaid shaft; a circumferential flange on the top of said bushingextending outwardly into said housing recess; and means forming acircumferential recess at the 'top end of said bushing and on theinterior side thereof, said recess extending downwardly adjacent saidshaft for at least the axial thickness of the aforesaid flange, wherebyside thrusts on said roller which are set up by grinding said coolmaterial in the bowl mill and which impose concentrated forces on saidbushings upper portion adjacent the flange are prevented from deformingthe bushing wall in a way that otherwise might occur with resultantseizure of said shaft.

3. In apparatus of the class described comprising a casing that definesa chamber through which hot gases flow for the purpose of drying lowtemperature material to be ground therein; a bowl rotatably mountedwithin said casing and having annpwardly extending side wall terminatingin a bowl rim; a shaft and means for suspending it at its upper endabove said bowl in .a substantially upright position and for holding theshaft against rotation about its axis, the lower portion of said shaftextending inside said bowl and below said bowl rim, the upper portionextending above said bowl rim and being exposed to the stream of theaforesaid hot gases flowing through said chamber and past said uppershaft portion; a roller surrounding the lower portion of said shaft forrotation with respect thereto and being in close contact with andsurrounded by the aforesaid low temperature material being pulverizedwithin said rotating bowl; a journal housing within said roller servingas a mounting for the roller; a bushing positioned said journal housingintermediate it and said shaft to rotate with the housing on the shaftand protruding at the upper end beyond the surrounding housingscontacting wall, said bushing having an inside diameter suflicientiylarger than said shafts diameter to provide clearance for thermalexpansion of said shaft; and means forming a circumferential recess atthe protruding end of said bushing and on the interior side thereof,said recess extending downwardly adjacent said shaft for at least thelength of the bushing protrusion, whereby side thrusts on said rollerwhich are set up by a grinding of said material between the roller andsaid rotating bowl and which impose concentrated forces on said bushingsupper portion adjacent its protruding end are prevented from deformingthe bushing wall in a way that otherwise might occur with resultantseizure of said shaft.

4. In apparatus of the class described comprising a casing that definesa chamber through which hot gases flow for the purpose of drying lowtemperature material to be ground therein; a bowl rotatably mountedwithin said casing and having an upwardly extending side wallterminating in a bowl rim; a shaft and means for suspending it at itsupper end above said bowl in a substantially upright position and forholding the shaft against rotation about its axis, the lower portion ofsaid shaft extending inside said bowl and below said bowl rim, the upperportion extending above said bowl rim and being exposed to the stream ofthe aforesaid hot gases flowing through said chamber and past said uppershaft portion; a roller surounding the lower portion of said shaft forrotation with respect thereto and being in close contact with andsurrounded by the aforesaid low temperature mate- 5 rial beingpulverized within said rotating bowl; a journal housing within saidroller serving as a mounting for the roller and having means forming acircumferential recess in its upper portion; a bushing positioned insaid journal housing intermediate it and said shaft to rotate with thehousing on the shaft and having an inside diameter sufficiently largerthan said shafts diameter to provide clearance for thermal expansion ofsaid shaft; a circumferential flange on the top of said bushingextending outwardly into said housing recess; and means forming acircumferential recess at the top end of said bushing and on theinterior side thereof, said recess extending downwardly adjacent saidshaft for at least the axial thickness of the aforesaid flange, wherebyside thrusts on said roller which are set up by a grinding of saidmaterial between the REFERENCES CITED The following references are ofrecord in the file of this patent:

UNITED STATES PATENTS Numf'cer Name Date 1,184,417 Capen May 23, 19161,921,044 Sparrow Aug. 8, 1933 2,100,734 Crites Nov. 30, 1937 2,112,359Crites Mar. 29, 1938 2,124,132 Bate et a1. July 19, 1938

